This invention relates to a pump for transferring and portioning pieces of meat, meat emulsions or any viscous material from a feed means such as a hopper to a packaging means.
In the production of whole muscle meat products, such as hams, large meat chunks are transferred from a hopper to a packaging station by way of a meat pump. At the packaging station, the meat is divided into portions and stuffed into casings.
One type of meat pump for transferring large pieces of meat from a hopper to a packaging station is described in U.S. Pat. No. 4,060,349 to Piereder A and comprises a continuous flow, oscillating meat pump in which a single vane oscillates between a pair of walls defining a V-shaped chamber. The pump described in this patent is advantageous in the production of whole muscle meat products since it can handle large pieces of meat and causes relatively little damage to the meat chunks, in comparison with other types of pumps which use screws or gears to transport the meat.
However, single vane oscillating pumps have the disadvantage that the vane must stop and change direction at the end of its path, resulting in a loss of efficiency which limits the output of the pump.
A further disadvantage of many presently used meat pumps is that they operate at relatively low pressures. Thus, when the meat product is expelled from the pump outlet, it must be further pressurized prior to being portioned and stuffed into a casing in order to ensure that it is uniform and free of voids. The pressurization, portioning and stuffing operations are typically performed by a single apparatus which is positioned at the outlet of the meat pump. Examples of presently used portioning and packaging devices are described in U.S. Pat. Nos. 4,188,767 and 4,417,434, both to Piereder.
In order to improve efficiency in the production of whole muscle meat products, it would be advantageous to provide a meat pump which is provides greater output than presently used single vane oscillating meat pumps and which is able to pressurize and portion the meat product to thereby perform at least some of the operations which would otherwise be performed by a separate portioning apparatus.
The present invention overcomes the disadvantages of the prior art discussed above by providing an improved method and apparatus for continuously pumping meat chunks from a feed means to a packaging station in which the meat product is pressurized as it is being pumped and is accurately divided into portions of predetermined size at an outlet valve, thereby eliminating the need for a separate portioning device.
The apparatus according to the invention comprises a twin vane concentric pump in which two movable vanes are rotatable in the same direction. At least one vane is rotating at all times, and therefore losses in efficiency due to stoppage and change of direction of the vanes are substantially reduced or eliminated.
Pressurization of the meat product is achieved by having one vane remain stationary between the inlet and outlet while rotating the second vane toward the outlet, thereby pressurizing the meat product and expelling it through the outlet.
The apparatus also comprises a control system which monitors the pressure and volume within the meat pump and controls the operation of the outlet valve to ensure that the meat product is pressurized to a predetermined pressure and that the portion size is accurately controlled.
In one aspect, the present invention provides an apparatus for dispensing predetermined amounts of a meat product, comprising: (a) a pump housing having an inlet opening, an outlet opening and a hollow interior, with a pump axis being centrally located in said hollow interior and surrounded by a side wall of said housing; (b) first and second vane means located in said hollow interior and rotatable about said pump axis, each of said vane means having a proximal edge proximate the pump axis and a distal edge proximate the side wall of the pump, said vane means dividing said hollow interior into a pair of chambers which are substantially sealed from one another, said chambers each having a volume which varies with relative rotation of the vane means; (c) drive means for rotating said first and second vane means independently of one another; (d) valve means associated with said outlet opening for opening and closing said outlet opening; (e) pressure sensing means for sensing a pressure in at least one of said chambers; (f) volume determination means for measuring a volume in at least one of said chambers; and (g) control means for controlling rotation of said vane means and operation of said valve means in response to pressure and volume information generated by said pressure sensing means and said volume determination means.
In a preferred aspect of the invention, the volume determination means measures the volume of at least one of the chambers by determining the relative positions of the vane means. Preferably, the pressure sensing means senses the pressure inside the outlet chamber, and the volume determination means determines the volume of the outlet chamber. In a further preferred aspect, the apparatus further comprises a stuffing horn associated with the valve means to receive said predetermined amounts of meat product from the valve means. In yet another preferred aspect of the invention, the predetermined amounts of meat product are severed from one another by closing the valve means. In yet another preferred aspect of the invention, the vane means are connected to drive shafts driven by separate drive means. In yet another preferred aspect of the invention, the drive means comprise servo drives. In yet another preferred aspect of the invention, the drive shafts comprise a first drive shaft for driving the first vane means and a second drive shaft for driving the second vane means, the drive shafts being coaxial with the second drive shaft being hollow and having a cylindrical bore through which the first drive shaft extends.
In another aspect, the present invention provides a method for producing predetermined quantities of a meat product using an apparatus comprising a pump housing having an inlet opening, an outlet opening and a hollow interior, with a pump axis being centrally located in said hollow interior and surrounded by a side wall of said housing; and first and second vane means located in said hollow interior and rotatable about said pump axis, each of said vane means having a proximal edge proximate the pump axis and a distal edge proximate the side wall of the pump, said vane means dividing said hollow interior into a pair of chambers which are substantially sealed from one another, said chambers each having a volume which varies with relative rotation of the vane means; said method comprising: (a) positioning said first vane means between said inlet and outlet openings and positioning said second vane means such that a first chamber of said pair of chambers communicates only with said inlet opening and a second chamber of said pair of chambers communicates only with said outlet opening; (b) with the valve means closed, moving the second vane means while the first vane means remains stationary, the second vane means being moved by rotation about said pump axis in a direction such that the volume of the second chamber is decreased and such that a pressure within said second chamber increases to a predetermined pressure and such that the volume of the first chamber is increased and said meat product enters said inlet opening; (c) with the pressure in the second chamber at the predetermined pressure, calculating the volume of the second chamber and, where the volume is less than said predetermined amount of the meat product, proceeding to step (g) or, where the volume is greater than said predetermined amount of the meat product, proceeding to step (d); (d) opening the valve means to allow the meat product to exit the second chamber, while continuing said rotation of said second vane means to maintain said predetermined pressure; (e) closing said valve means once the predetermined amount of the meat product has been dispensed from the outlet opening; (f) repeating steps (c) to (e) until the volume measured in step (c) is less than the predetermined amount of the meat product; (g) rotating the first and second vane means in the same direction until the second vane means is positioned between said inlet and outlet openings and the first vane means is positioned such that the first chamber is in communication only with the outlet opening and the second chamber is in communication only with the inlet opening.
In a preferred method of the present invention, the predetermined pressure is up to about 35 bar. In yet another preferred aspect of the present invention, in which the apparatus further comprises a stuffing horn, the method further includes passing the predetermined quantities of meat product through the stuffing horn into a casing.